Addison -
Yea, I've had good luck with the Diabolo, Exact Heavy (18.13gr) in mine (great gun..!).
While I don't shoot great distances, I do shoot offhand. No crutches here. In my short range...(a hair over 17 yards), I can put a magazine worth into a dime sized hole on a good day and a nickle sized hole pattern on most any day (again...offhand).
I tried four different weight (12.3 to 18.1) and brand pellets, and all three of my short guns seem to like the above Exact Heavies best. Seems the heavier pellets I loaded, the tighter the groups got. Don't know if it's the weight, or the brand. I should try a different brand, of 18gr. pellet and see what happens.
Mike